# Re: st: Stratified Sampling

 From "Eric G. Wruck" To statalist@hsphsun2.harvard.edu Subject Re: st: Stratified Sampling Date Fri, 9 Sep 2005 20:04:09 -0400

```Of course there is some theory.  The one time I made use of stratified sampling I relied on William G. Cochran's "Sampling Techniques" (1977) published by Wiley & Sons.  Basically, you want to sample in proportion to the variance of the variable of interest.  In this way your sample is likely to be more informative.

Good luck,

Eric

>Hi,
>
>I am teaching a sophomore social statistics course.
>I've been covering sampling, especially stratified
>sampling this week.
>
>The students need some assistance in explaining the
>weighting procedures associated with disproportionate
>stratified sampling.  How can I demonstrate this in a
>class with a concrete example.
>
>Also, is there any guidelines as to how to oversample
>a particular stratum?  Assuming i have 2 groups (males
>are 20% and Females=80%). If I am drawing a sample of
>100 students - it means I would end up with 20 males
>and 80 females.  If i need to oversample the males,
>what values should i chose - 30, 40, 50? - is the
>choice really arbitrary or is guided by theory or
>calculations?
>
>I will appreciate your thoughts on this.
>
>Regards, YC

--

===================================================

Eric G. Wruck
Econalytics
Columbus, OH  43209

ph:      614.231.5034
cell:    614.330.8846
eFax:    614.573.6639
eMail:   ewruck@econalytics.com
website: http://www.econalytics.com

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